Device for stabilizing and homogenizing liquid mixtures



y 1952 s. H. B. ZACHARIASSEN 2,595,376

DEVICE FOR STABILIZING AND HOMOGENIZING LIQUID MIXTURES Filed May 12,1949 INVENTOR. 511'9 Q/o/ger @jame Zacharias-$622 :in the {homogenizingthey can not therefore he 'used.

Patented May 6, 1952 DEVICE FORSTABILIZINGAN D H'OMOG- .IENIZING LIQUIDiMIXTURES ZStigfHolgerLBjame Zachariass'n, Stockholm, Sweden, assignorto 'Aktiebolaget Separator, Stockholm, Sweden, a corporation of SwedenApplication Mayl2, 1%l49,.;S.erial.N0.;92;774 LInQS-weden Mayi14,.19.48

.3 Claims. 1

This. invention relates to-a methodand-appara- 'itus for stabilizing andhomogenizing .liguid mix- ".turespsuch asmilk.

IHomogenizi g -machines of the known types with maximum efficiency areso-called'high pressure homogenizers in which the liquid under treatmentis forced'through very narrow slots under apressure ranging from'50 to600 atmospheres. T e basic principle inall these machines Iis.tosubjectthe fator water-particles to be atomized .to such considerabledeforming, when .they arepassing through .the narrow slot, that they are.divided intoa numberofsmallerparticles. As .the energy necessary Iforgenerating themequisiteihigh pressure .can nothe recovered, homogenizing.machines of ithis t ne entail very :jhiigh. operating costs.

"Becauseof this, a great "number of .other con zstructions, ;so-calledlow pressure homogenizers, 1havefbeen.;devised; which work upon "verydiffer:

='.entj, rinciples and .in which the homogenizing is :efiectedflgmmeans.ofpressures between'll and ratmospheres. The power consumption .ofthese machines is, "of ,c;ourse. .correspon'ding'ly smaller,

but theirihomogenizing effect onthe whole-also correspondstbtheusedpressure, so that. they can zgenerallybe :used only, for comparativelysimple problems. "Whenihigh requirements mus'txhemet "Z'Thehomogenization of milk and :cream g re-=sents-ardifflcriltprob1em,ibecause inthis case "an "atomization .ofthe'fat globules "to maximum "2a and preferablyi r only, or'.less,1'isrequired. Heretofore it waspossible to'solvethis problem only'by. meansof high pressure homogenizers operated by pressures of at least50"to1'00 atmospheres. jI-Iomogenizing of'milk "has theref'ore not found "theprac'tical and jexten'siveuse .whichcould have been expected. I

Verycomprehensivetestshhoweverjhaveishown :that it ,is "possible totreat-milk and cream by means of considerably lower pressures and yet toobtain the :same final quality of the product: by

abandoning the principle onwhich'the high pressure homogenizers workandto im-part instead, in a first step,;a comparatively high velocity'tothe liquid,'if"possible, without-losses and then'totreat Lit iii-suchaway,iin a-secon'd step,=tha t the velocity:is=conyerted,'atleastlargelyyintogpure liquidfri'ction atll'iighest-possible "turbulency' and avoiding,

"as fariaspos sible, 'any friction with thwsurrounding walls. r Testshave shown "that, when work- "ing on this-prin'ciple, averagediametersof the fat 'g'lobules'ranging from '1 :1 to -13 can beobtained,when working with-pressuresof only 12 to 25stkept clean and'hygienicwithless work.

- mospheres in the homogenizer, according totheinper cent is achieved.Furthermore, it is possible to dispense with the inletan'd-outletvalveswhich "complicate the useofhigh pressure' homogenizers, sothatgtaking everything into "account, a -'con- "structionisobtainedwhich, whileihaving the'same efficiency, requires only a fraction oithecon- :sumption of materialran'd power of piston-pumps and is. 'zbesides,considerably simpler an d "cant-be According to the invention, theliquid'is supplied from-asource of pressure and-sprayed into aiclosedwhirl-chamber in which'the velocity energy is converted, asfar aspossible, into ,pure liquid friction. The dimensions of "the whirl-"chamber must be determined according "to "the material to be treatedand to -prevailing "condiitions. The higher the pressure at *a certain"desired effect, the longer the whirl-chamber "must be, reckoned in theaxial direction of the liquid jet issuing from the nozzle. -tancefromthe nozzle'are determinedby'thevls- Its-volume and "discosity of'theliquid to be treated. A general rule is that there should only bethe'lowestpossible pressure, that is, a few atmospheres in the whirl-;chamber or,iif theproperties of the'liquid make it-possibleapressureapproac'hing n11. Ifin-the case of 'mil-k, for example, thehomogenizing is considered satisfactory if no cream plugs "are formedwithin 48hours, a homogenizing device with-thefollowing data can beused: pressure 15- '30 kgs./cm'3 diameter of whirl-chamber 15-12 mms.,length of whirl chamber 50-70'mms -dista-nce between outlet edgeof'whirl-chamberand liquid outlet of nozzle greater than-'4"mms. "If,

for example, 12 per'zcent-creamiis homogenized by means of a higher-pressu refthe 'distancershould be greater, eventually as much 'as'2'0:mms; I'f a'still richer cream is-treated, the otl'rerdata-of theWhirl-chamber must also be changed-and-"cle- "termined according to-theviscosity.

The source of pressure 'may generally Eb screw pump or possibly atoothed-wheel or centrifugal pump. When particularly high requirementsare put on the homogenized liquid and when, for onereason or other, theliquid must also be separated, the source of pressure is, according tothe invention, the rotating bowl of a separator in which the entirehomogenizing device is permanently fitted so that it also rotates.Depending upon the weight of the liquid and the diameter of theseparator bowl and its velocity, there is in the outer layer of the bowla pressure in the order of 30 to 60 atmospheres. After the liquid haspassed through the homogenizing device, it discharges into thesurrounding vessel so that, in addition to the homogenizing, also aqualitative control of the liquid with regard to particle size can bemade in the separator. Fat and water particles of undesirable dimensionsare separated in the bowl and fed to the homogenizing device for furthertreatment. Since the pressure of 30 to 60 atmospheres available in theseparator bowl insures a very satisfactory atomization of the particleswhen homogenizing according to the invention, that part of the liquidflow which has been treated in the homogenizing device may generally bedirectly mixed with that part of the liquid flow which has passedthrough the separator.

If it is particularly important for the discharging liquid not tocontain particles over a certain size, the liquid issuing from thehomogenizing device is returned and mixed with the liquid fed to theseparator. By this combination, which is especially advantageousfor.mill and cream, only part of the whole quantity of the liquid ispassed through the homogenizing device,

which may be made correspondingly smaller. ..With a view to avoidingadmixture of air, the

receiving vessels of the separator should preferably be kept undervacuum. The effect of the described device may be improved by forcingthe liquid out of the nozzle not only with an axial velocity but alsowith a rotative motion imparted to it in advance of the nozzle byfeeding it in a tangential direction into its antechamber. In thismanner the velocity gradient is also increased, especially in thewhirl-chambers, and the result of the homogenizingis improved. Theresult of the homogenizing is generally improved'as the turbulentmotion. in the whirl-chamber is increased. Consequently, the result maybe improved by providingparts in the whirl-chamber which cause strongturbulence. These parts may, for example, consist of chips or bodies ofother shape which are particularly disadvantageous from a flowstandpoint, that is to say, are provided with sharp corners, edges, etc.at which whirls are formed. Since such parts can not be keptsufficiently clean, they preferably consist of a single unit which,after completion of the work, can be thrown away and replaced bya newone.

The accompanying drawing shows by way of example some embodiments of theinvention.

Fig. l is a schematic view illustrating the basic principle of theinvention;

Fig. 2 is a similar view, but'in greater detail, illustrating thepractical construction of an ap paratus of this type;

-Figs. 3 and 4 are diagrammatic illustrations of a cyclone forincreasing the velocity gradient by introducing the liquid tangentiallyinto the apparatus, and

Fig. 5 is a vertical sectional view of a cen- I trifugal separator bowlprovided with an homog- 4 enizing device in accordance with theinvention.

The liquid is fed from a nozzle I into a whirlchamber 2 in which theconversion of velocity energy into liquid friction takes place, anyfriction against the surrounding walls of the bowlchamber 2 therebybeing as far as possible avoided. As shown in Fig. 2, the nozzle 3 ismovable in an axial direction in a sleeve 4, so that the distancebetween the liquid outlet of the nozzle and the outlet edge of thewhirl-chamber 5 can be adjusted by a movable part 6. A manometer 1 isused for controlling the pressure in the whirl-chamber. Figs. 3 and 4show the use of a cyclone 8 for increasing the velocity gradient byintroducing the liquid tangentially into the chamber 2 (with a rotatingmotion about the axis of the chamber). Referring to Fig. 5, from aliquid, which may be fed into the bowl I0 through the hollow spindle orinlet 9, that part which contains fat and water particles ofcomparatively large diameters is separated in the separating chamberbetween the discs ll, according to the type of emulsion under treatment.According to the type of emulsion being treatedwater in oil or oil inwater-the outer (heavier) or the inner (lighter) phase in the separatorbowl is led to the homogenizing device I3 for further treatment. Fromthe homogenizing device the liquid flows into the collecting vessel l2,whence it either proceeds to that part which has passed directly throughthe separator or is remixed with the liquid to be fed to the separator.

In the whirl-chamber 2 (or 5), which may be stationary, the liquiddischarged at high velocity from nozzle l (or,3) is caused to undergo-awhirling motion before it is discharged over the periphery of thewhirl-chamber at its open end, as shown by the arrows in Figs. 1 and 2,whereby the liquid velocity is rapidly converted at least largely intoliquid friction. It will be understood that when the cyclone 8 isemployed to increase the velocity gradient, the cyclone gives the liquida rotating motion as it passes through the nozzle into theWhirl-chamber, as. shown by the arrow in Fig. 4. When the homogenizingdevice is incorporated in a centrifugal separator bowl, as shown in Fig.5, the homogenizer I3 is essentially the same as those shown in Figs. 1and 2, inthat it has a'nozzle for bringing the liquid particles to highvelocity, and a whirl-chamber for receiving the nozzle discharge andrapidly converting the liquid velocity (radial) largely into liquidfriction before it is discharged into the stationary collecting vessell2, which preferably kept under vacuum by suitable means (not shown). Asillustrated in Fig. 5, the larger particles of the liquid are separatedas a lighter component and pass from the central part of the bowloutward through a bottom passage to the nozzle which opens into thewhirl-chamber l3 of the homogenizer, the homogenizer being shown onlygenerally in Fig. 5. The heavier liquid from which the larger particlesare separted in the bowl passes upwardly under the bowl top and isdischarged separately.

I claim:

1. A device for stabilizing and homogenizing liquid mixtures, whichcomprises a centrifugal separatorbowl having an inlet for the liquid anda separating chamber communicating with the inlet, a nozzle in the bowlfor receiving the municating with the nozzle for rapidly converting theliquid velocity of said particles at least largely into liquid frictionwith substantial turbulence, to homogenize the mixture of saidparticles, and a stationary vessel surrounding the bowl for receivingthe homogenized particles from the whirl-chamber.

2. Apparatus for stabilizing and homogenizing emulsions, which comprisesa centrifugal bowlhaving a separating chamber for centrifugallyseparating the emulsion into homogenized and non-homogenized components,the bowl having an outlet for the separated homogenized component, anhomogenizing device at the peripheral part of the bowl and having anoutlet for a second homogenized component, and means in the bowl forconducting said non-homogenized component from the separating chamber tosaid homogenizing device.

3. Apparatus according to claim 2, in which the homogenizing deviceincludes a whirl-chamber through which the non-homogenized componentpasses from said conducting means to said second outlet, thewhirl-chamber being adapted to effect rapid conversion of the velocityof said last component at least largely into liquid friction withsubstantial turbulence.

STIG HOLGER BJARNE ZACHARIASSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 336,324 Johansson Feb. 16, 1886439,173 Newberry et al. Oct. 28, 1890 1,406,791 Werner Feb. 14, 19221,846,076 Anderson Feb. 23, 1932 1,866,638 Fawcett July 12, 19321,925,049 Howard Aug. 29, 1933 2,060,239 Peltzer Nov. 10, 1936 FOREIGNPATENTS Number Country Date 539,016 France June 19, 1922 584.860 GermanySept. 25, 1933

